1. Field of the Invention
The invention relates to a device for determining the oxygen content of a gas mixture or gas matrix.
2. Description of the Prior Art
Oxygen and oxygen molecules have the property of being paramagnetic. This means that in an inhomogeneous magnetic field, a force is exerted on oxygen molecules. This physical effect is used in a known planner to determine oxygen content. When this is done, a directed force, proportionate to the oxygen content or quantity, is produced in the inhomogeneous magnetic field. Generally, a sensor part for measuring this effect consists of a dumbbell-shaped functional unit that can be displaced and rotated in the inhomogeneous magnetic field. As mentioned, the oxygen molecules held on both sides of the dumbbell-shaped functional unit undergo deflection in the magnetic field, resulting in a rotary displacement of the dumbbell-shaped arrangement. This rotation is compensated for by a current through a compensation coil. The position or displacement of the dumbbell is determined via a mirror, and the mirror detected position is thus proportionate to the detectable oxygen content. As noted, oxygen measurement devices of this type, which use tile magneto-mechanical method described above, have a dumbbell-shaped arrangement with corresponding gas volumes. The dumbbell, which is located within the influence of an inhomogeneous magnetic field, is rotatably suspended by a clamping band. In the presence of oxygen, the dumbbell rotates in the magnetic field to a greater or lesser extent, in a manner proportionate to the share of oxygen. By optically determining the rotational angle, it is possible, in the manner described above, to determine the share of oxygen.
Devices of this type are usually operated in compensatory operation. This means that there is a compensation coil, through which a current is run to compensate for the magnetically-mechanically produced rotation. A light beam is directed upon a mirror, which is connected to the dumbbell, and projected by reflection onto a light-sensitive sensor. The strength of the displacement is proportionate to the current and to the concentration of oxygen. The oxygen concentration can therefore be derived from amount of current needed to compensate for the rotation.
In known designs, the aforementioned components, which essentially comprise the dumbbell, magnetic elements, the rotatable functional unit and the electric compensation device, including the mirror and sensors, are produced as discrete parts and then assembled. This is an expensive method, not only because assembling the individual parts is costly, but because adjusting them to one another is, too.